Recycled plastic material, electronic apparatus having the recycled plastic material method of manufacturing plastic part, method of manufacturing the recycled plastic material, and method of reusing plastic material

ABSTRACT

When thermoplastic is recycled by a general recycling process alone, only a low-quality recycled plastic material having physical property values lower than a virgin material can be obtained. A recycled plastic material of this invention is made from laser-engraved thermoplastic, metal-containing thermoplastic, thermoplastic used in an inkjet apparatus, or thermoplastic to which an ink or its composition have stuck. This recycled plastic material is manufactured by pulverizing any of these thermoplastics, cleaning the pulverized thermoplastic, removing a cleaning solution from the cleaned thermoplastic to dry it, and removing from the dried thermoplastic solid matter other than the thermoplastic.

FIELD OF THE INVENTION

[0001] The present invention relates to a recycled plastic material madefrom a thermoplastic product, an electronic apparatus using thisrecycled plastic material a method of manufacturing a plastic part, amethod of manufacturing the recycled plastic material, and a method ofreusing a plastic material.

BACKGROUND OF THE INVENTION

[0002] Recently, with increasing consciousness of environmentalprotection, the movement of recycling and reusing petrochemicals, inaddition to conventionally recycled metal materials, has, become active.Only in Japan territory, “Waste Disposal Law” (Law No. 137, 1970), “Lawfor Promotion of Sorted Collection and Recycling of Containers andPackaging” (Law No. 112, 1995), and “Law for Recycling of SpecificHousehold Appliances” (Law No. 97, 1998) have been enforced. As theselaws and regulations have been enacted, recycling of thermoplastics ofsome large household appliances and automobiles has been accelerated.

[0003] Many of these recycling activities,-however, are thermalrecycling using thermoplastics as a heat source and recycling forcascade use in which a lowering of the physical properties of recycledthermoplastics is of little problem. Therefore, little care is taken ofsorting of thermoplastics contained in electronic apparatuses, such ascopying machines, facsimile machines, personal computers and theirperipheral devices (printers, keyboards, and displays), and inexpendables (e.g., toner cartridges and ink cartridges) of theseelectronic apparatuses. As a consequence, thermoplastics to be recycledcontain various contaminants, so it is impossible to obtainthermoplastics which can be reused as the same products or parts.

[0004] Also, even when electronic apparatuses and their components (tobe collectively referred to as electronic apparatuses hereinafter) aremanufactured using recycled thermoplastics, these thermoplastics are inmost cases used as packaging containers and packing materials. That is,recycled plastic materials are not used to manufacture the originalelectronic apparatuses. In particular, labels, seals, and decals (to becollectively referred to as labels hereinafter) on which explanation ofoperation of an electronic apparatus is printed are pasted on externalparts of electronic apparatuses. The base material or adhesive of such alabel pasted on an external part cannot be removed only by cleaning. Atpresent, the adhesive sticking to the part must be cut away using acutter or the like, and this increases the recycling cost.

[0005] Analogously, an electronic apparatus incorporating an ink holdingmember for holding ink, represented by an inkjet apparatus for printingdesired character information and image information (to be collectivelyreferred to as image information hereinafter) by discharging inkdroplets from discharge orifices onto an arbitrary printing medium, suchas paper, cloth, plastic, or metal, or a cartridge containing ink, has apart to which ink and its components have stuck. When this part isdirectly recycled, the residual ink and its components deteriorate thephysical properties and change the hue of the part. This makes recyclingof such parts very difficult. Furthermore, these inkjet apparatusescontain not only inks but also pollutants such as a lubricating agent(e.g., grease) for mechanical driving portions. Hence, these inkjetapparatuses require a more complicated process and a higher recyclingcost than those of plastic material recycling that can be commonlythought of. For this reason, no recycling using components of inkjetapparatuses as materials have been performed.

[0006] As methods of recycling in this field, some techniques have beendisclosed in Japanese Patent Laid-Open Nos. 5-301222 and 7-323560 andPatent No. 2513106. The technique disclosed in Japanese Patent Laid-OpenNo. 7-323560 has disclosed only a method of directly reusing parts to berecycled by cleaning.

[0007] The technique disclosed in Japanese Patent Laid-Open No. 5-301222compensates for a lowering of the physical property values of recycledplastic materials by additives. The technique disclosed in Patent No.2513106 compensates for a lowering of the physical property values ofrecycled plastic materials by polymer selection.

[0008] On the other hand, a so-called laser engraving technique is knownas a method of displaying desired image information by changing thecolor of the surface of a plastic part. This technique can printoperation instructions of an apparatus directly on a part, so the costand the number of steps necessary to remove a pasted label can bereduced. Details of this laser engraving technique are described inJapanese Patent Publication Nos. 61-11711 and 62-59663. However, thesepatent publications have disclosed only the basic techniques of laserengraving and do not exhibit any practical method pertaining torecycling of laser-engraved plastics.

[0009] When the physical properties of a material are taken intoconsideration, the range of use of a recycled material greatly widens ifphysical property values equivalent to those of its original virginmaterial are guaranteed. To guarantee physical property values, however,if the addition of additives or the selection of polymers is performedin the recycling process as in the aforementioned prior art, the cost ofcontrol of input amounts of additives or the cost of selection ofpolymers increases the total cost of recycling. This can postponeswitching from virgin materials to recycled materials.

[0010] Also, as one characteristic of thermoplastics, linear patternssuch as black streaks or silver streaks sometimes form on the surface ofa molded product owing to the influence of heat applied during molding.These patterns are primarily caused by the molding conditions. However,if foreign matter is mixed in a material itself, a black dot oftenappears on the surface.

[0011] When laser engraving which discolors or carbonizes the surface ofan object to be processed is performed, the engraved portion itself canbecome foreign matter if the object is thermoplastic. Not only in laserengraving but also during use, collection, and disassembly of products,rubbish, dust, and foreign matter adhere to the surfaces of parts to berecycled. If these parts are not sufficiently cleaned and foreign matteris not well removed, larger amounts of foreign matter than when virginmaterials are used are produced when these parts are used as recycledmaterials. This can impair the product value of especially externalparts of electronic apparatuses.

SUMMARY OF THE INVENTION

[0012] The present invention, therefore, has been made in considerationof the above situation, and has as its object to provide a high-qualityrecycled plastic material of thermoplastic whose physical propertyvalues lower little from those of a virgin material, without adding anystep to commonly performed recycling steps of pulverizing, cleaning,removable of a cleaner, drying, and removal of metals and foreign matterand, more particularly, to provide a recycled plastic material made fromthermoplastic used in an inkjet apparatus including ink and inkcomponents.

[0013] It is another object of the present invention to provide anelectronic apparatus using the above recycled plastic material.

[0014] It is still another object of the present invention to provide amethod of manufacturing a plastic part using the recycled plasticmaterial.

[0015] It is still another object of the present invention to provide amethod of manufacturing the recycled plastic material.

[0016] It is still another object of the present invention to provide amethod of reusing a plastic material.

[0017] To solve the above problems and achieve the objects, the presentinvention is constituted as follows.

[0018] The first mode of the present invention is a recycled plasticmaterial made from laser-engraved thermoplastic.

[0019] The second mode of the present invention is a recycled plasticmaterial manufactured by pulverizing laser-engraved thermoplastic,cleaning the pulverized thermoplastic, removing a cleaning solution fromthe cleaned thermoplastic to dry the thermoplastic, and removing fromthe dried thermoplastic solid matter other than the thermoplastic.

[0020] In the first and second modes of the present invention, therecycling process of the recycled plastic material does not require anylabel peeling step. Also, since no paint such as used in silk screenprinting sticks to the material, the recycling process can besimplified, and deterioration of the hue of the obtained recycledplastic material can be prevented.

[0021] The third mode of the present invention is a recycled plasticmaterial made from thermoplastic containing a metal.

[0022] The fourth mode of the present invention is a recycled plasticmaterial manufactured by pulverizing thermoplastic containing a metal,cleaning the pulverized thermoplastic, removing a cleaning solution fromthe cleaned thermoplastic to dry the thermoplastic, and removing fromthe dried thermoplastic solid matter other than the thermoplastic.

[0023] In the present invention, not only metals (including metalparticles) contained in thermoplastic as a raw material but also mostmetal pieces which can be mixed when the raw material is pulverizedduring the recycling process can be easily removed. This enhances theeffect of finally removing solid matter other than the thermoplastic.Therefore, contamination is very little, so recycled plastic having highexternal appearance quality can be obtained.

[0024] The fifth mode of the present invention is a recycled plasticmaterial made from thermoplastic used in an inkjet apparatus.

[0025] The sixth mode of the present invention is a recycled plasticmaterial manufactured by pulverizing thermoplastic used in an inkjetapparatus, cleaning the pulverized thermoplastic, removing a cleaningsolution from the cleaned thermoplastic to dry the thermoplastic, andremoving from the dried thermoplastic solid matter other than thethermoplastic.

[0026] The seventh mode of the present invention is a recycled plasticmaterial made from thermoplastic to which ink and components thereof aresticking.

[0027] The eighth mode of the present invention is a recycled plasticmaterial manufactured by pulverizing thermoplastic to which ink andcomponents thereof have stuck, cleaning the pulverized thermoplastic,removing a cleaning solution from the cleaned thermoplastic to dry thethermoplastic, and removing from the dried thermoplastic solid matterother than the thermoplastic.

[0028] When a product, such as an ink cartridge, which contains ink andan ink holding member impregnated with the ink is to be recycled, anexternal member of the product must be separated from the ink holdingmember. If this external member is cut by a cutter or the like, aportion of the ink holding member, such as foamed polyurethane, is oftenwelded to the cut surface. This welded foamed polyurethane cannot bewashed away by cleaning operation alone. Processes such as cleaningsolution removal and drying allow easy separation of the foamed urethanefrom the external member. The state of adhesion of rubbish, dust, andforeign matter to the product to be recycled cannot be specified. Hence,by executing the processing following the aforementioned procedure,effective foreign matter removal is performed with a minimum necessaryload.

[0029] The ninth mode of the present invention is an electronicapparatus comprising the recycled plastic material according to any oneof the first to eighth modes described above.

[0030] When the recycled plastic material of the present invention isused in electronic apparatuses rapidly increasing in product shipmentquantity recently, the use and spread of this recycled plastic materialare promoted.

[0031] The 10th mode of the present invention is a method ofmanufacturing a plastic part, comprising the steps of disassembling anelectronic apparatus having a laser-engraved thermoplastic part,separating the thermoplastic part from the disassembled electronicapparatus and pulverizing the thermoplastic part, cleaning thepulverized thermoplastic, removing a cleaning solution from the cleanedthermoplastic to dry the thermoplastic, removing from the driedthermoplastic solid matter other than the thermoplastic, and molding athermoplastic part of the electronic apparatus by using thethermoplastic, from which the solid matter is removed, as a rawmaterial.

[0032] The 11th mode of the present invention is a method ofmanufacturing a plastic part, comprising the steps of disassembling anink container used in an inkjet apparatus, separating a thermoplasticpart from the disassembled ink container and pulverizing thethermoplastic part, cleaning the pulverized thermoplastic, removing acleaning solution from the cleaned thermoplastic to dry thethermoplastic, removing from the dried thermoplastic solid matter otherthan the thermoplastic, and molding a thermoplastic part of the inkjetapparatus by using the thermoplastic, from which the solid matter isremoved, as a raw material.

[0033] The 12th mode of the present invention is a recycled plasticmaterial manufactured by recycling apart molded from a thermoplasticmaterial, characterized in that an impact strength of the recycledplastic material is 80% or more of a virgin plastic material, and a meltflow rate (MFR), indicating the flowability of a plastic material, ofthe recycled plastic material is 90 to 120% of the virgin plasticmaterial.

[0034] The 13th mode of the present invention is a method ofmanufacturing a recycled plastic material, characterized in that inorder to recycle a part molded from a thermoplastic material, plastic isrepelletized through steps of pulverization, cleaning, drying, andforeign matter removal of the molded part, and an impact strength and amelt flow rate (MFR) of the plastic pellets are adjusted within theranges of predetermined values.

[0035] The 14th mode of the present invention is a method of reusing aplastic material, characterized in that a part is molded from a plasticmaterial, the molded part is used as a part after a laser engravingdisplay is formed on the molded part, a recycled plastic material isformed through steps of pulverization, cleaning, drying, and foreignmatter removal of the part, and an impact strength of the recycledplastic material falls within a predetermined range of an impactstrength of a virgin plastic material.

[0036] The 15th mode of the present invention is a method of reusing aplastic material, characterized in that a plastic material is moldedinto an ink container and used as a part, a recycled plastic material isformed through steps of pulverization, cleaning, drying, and foreignmatter removal of the part, and physical property values of the recycledplastic material fall within predetermined ranges of physical propertyvalues of a virgin plastic material.

[0037] The 16th mode of the present invention is a method ofmanufacturing a recycled plastic material, characterized in that arecycling raw material is obtained by successively performing, in theorder named, the pulverizing step of pulverizing a part molded from athermoplastic material by using a mesh screen of 4 to 10 mm, thecleaning step of cleaning a pulverized material obtained in thepulverizing step by using 10 parts by weight of water as a cleaningsolution with respect to 1 part by weight of the pulverized material,the dehydrating step of dehydrating the pulverized material cleaned inthe cleaning step by centrifugal dehydration to set a moisture contentto not more than 0.30 wt %, the foamed body removing step of removing,by air classification, a foamed body having a bulk density difference ofnot less than 0.5 from the pulverized material dehydrated in thedehydrating step, the first metal removing step of removing a metal fromthe pulverized material by using a magnet having a residual magneticflux density of not less than 1 tesla, and the second metal removingstep of removing a metal by using a metal detecting/removing device, andrecycled plastic pellets are obtained by successively performing, in theorder named, the mixing step of sufficiently mixing the recycling rawmaterial, the recycling step of melting, kneading, and recycling therecycling raw material by an extruder, and the pelletizing step ofpelletizing the material recycled in the recycling step.

[0038] Other objects and advantages besides those discussed above shallbe apparent to those skilled in the art from the description of apreferred embodiment of the invention which follows. In the description,reference is made to accompanying drawings, which form a part thereof,and which illustrate an example of the invention. Such example, however,is not exhaustive of the various embodiments of the invention, andtherefore reference is made to the claims which follow the descriptionfor determining the scope of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

[0039]FIG. 1 is a perspective view showing the external appearance of aninkjet printer as an object of the present invention;

[0040]FIG. 2 is a perspective view showing the state in which anoperation cover of the inkjet printer shown in FIG. 1 is opened;

[0041]FIG. 3 is an enlarged front view of the operation cover shown inFIG. 2;

[0042]FIG. 4 is a view showing the concept of an example of a recycledplastic material manufacturing system according to the presentinvention;

[0043]FIG. 5 is a sectional view showing the structure of a cleaningtank incorporated into the manufacturing system shown in FIG. 4;

[0044]FIG. 6 is a perspective view showing the external appearance ofanother inkjet printer as an object of the present invention;

[0045]FIG. 7 is an enlarged front view of an operation cover of theinkjet printer shown in FIG. 6;

[0046]FIG. 8 is a perspective view showing the external appearance of anexample of a cartridge used in the inkjet printer;

[0047]FIG. 9 is an exploded perspective view of the cartridge shown inFIG. 8;

[0048]FIG. 10 is a view showing, together with FIG. 11, the concept ofthe work of recycling the cartridge shown in FIG. 8, in which the statewherein a printed circuit board and a cover plate are detached isdepicted;

[0049]FIG. 11 is a view showing, together with FIG. 10, the concept ofthe work of recycling the cartridge shown in FIG. 8, in which the statewherein an ink tank is cut to remove an ink holding member is depicted;

[0050]FIG. 12 is a view showing the concept of the work of conducting abreaking strength test on the cover plate shown in FIGS. 8 and 9 byusing a push-pull gauge;

[0051]FIG. 13 is a view showing the physical property values of plasticmaterials of the Example 1 and comparative examples;

[0052]FIG. 14 is a view showing Example 2 and its comparative examples,and the physical property values of plastic materials of Example 3;

[0053]FIG. 15 is a view showing the physical property values of plasticmaterials of the Examples 2 and 3;

[0054]FIG. 16 is a view showing the physical property values of plasticmaterials of the Example 4 and comparative examples; and

[0055]FIG. 17 is a view showing the physical property values of plasticmaterials of the Example 5.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0056] In the recycled plastic material according to the first or secondmode of the present invention, it is preferable that the area of laserengraving be 2% or less of the surface area of a plastic part to berecycled, the width of one scanning line of laser engraving be 0.15 mmor less, or the depth of laser engraving be 0.05 mm or less.

[0057] This restricts the discolored matter and carbonization amount ofthermoplastic by a laser and enhances the cleaning effect duringrecycling, thereby minimizing the production of foreign matter on thesurface of a molded product. Also, since the amount of foreign matter issmall, a lowering of the physical property values is suppressed, so thequality of the recycled plastic material can be held substantially thesame as the virgin material.

[0058] In the recycled plastic material according to the fourth mode ofthe present invention, pulverized thermoplastic can also be separatedfrom metals before being cleaned.

[0059] Also, the step of removing solid matter other than thermoplasticcan have at least one of gravity separation which uses the true densitydifference between the thermoplastic and the foreign matter, magneticseparation which uses magnetic force, and metal separation which uses aneddy current. Metal separation using an eddy current is employed formetals, except for ferroelectric substances, which cannot be separatedby magnetic force.

[0060] In the recycled plastic material according to the fourth, sixth,or eighth mode of the present invention, thermoplastic can be pulverizedby a high-speed pulverizer by using a mesh screen within the range of 4to 10 mm, and fine plastic particles of 2 mm or less, metal particles,and dust particles can be removed using a shaking screen.

[0061] If the mesh screen for pulverization is less tan 4 mm, the amountof fine particles increases to increase losses during cleaning anddrying steps, thereby decreasing the yield. In contrast, if the meshscreen is larger than 10 mm, the size of a pulverized product becomestoo large. This readily causes clogging and the like in the subsequentprocessing and lowers the workability.

[0062] Consequently, most of metals which cannot be removed by selectionbefore pulverization and metal pieces mixed during pulverization can beremoved. This enhances the effect of removing final solid matter otherthan thermoplastic. So, recycled plastic having very littlecontamination and having excellent external appearance quality can beobtained.

[0063] In the recycled plastic material according to the sixth mode ofthe present invention, ink and its components, paper dust, and dustparticles sticking to thermoplastic can be removed by cleaning thisthermoplastic. Also, pulverized thermoplastic can be separated fromforeign matter before being cleaned. Furthermore, a cleaning solutionused in cleaning can be filtered through a filter having a mesh withinthe range of 25 to 200 μm to reuse the filtered cleaning solution.

[0064] Most preferably, a cleaning solution used in cleaning is directlyreused. However, a cleaning solution used in cleaning is colored bycoloring agents contained in ink, so it is basically difficult todirectly reuse this cleaning solution owing to suspended fine particlesand the problem of color. In particular, particulate contamination hasadverse effect on the physical properties of a recycled plastic materialand therefore must be removed. The smaller the mesh size (filteringaccuracy) of the filter used, the more the physical properties of therecycled plastic material improve, but the more easily filter cloggingtakes place. The use of a filter having a mesh within the range of 25 to200 μm can improve the physical properties of a recycled plasticmaterial obtained and solve the problem of filter clogging at the sametime.

[0065] A cleaning solution can contain at least one of an additive foradjusting the pH concentration and a surfactant.

[0066] The pH concentration of ink must be measured from the ink itself.For example, even if a dye contained in ink is acidic, the ink itself isalkaline in some cases.

[0067] For instance, when the ink is acidic, a cleaning solutiondissolved in the ink also becomes acidic, and this cleaning solutionbecomes an environmental load because its acidic concentration risesduring the process of reuse. Additionally, cleaning using only water isunsatisfactory depending on the type of ink, so a large amount of watermust be used for long time periods in order to enhance the cleaningeffect. By the addition of an additive for adjusting the pHconcentration and a surfactant, these inconveniences are solved, and thecleaning process is completed within a short time.

[0068] Similarly, when the ink is alkaline, the alkali concentration ofa cleaning solution rises during the process of reuse, and this cleaningsolution becomes an environmental load.

[0069] When the ink is neutral, a cleaning solution is filtered toremove foreign matter, and the resultant cleaning solution is directlyreused.

[0070] Tap water (pH≈7.6, weakly alkaline) can also be used as acleaning solution. It is also effective to consider the pH concentrationof this cleaning solution on the basis of tap water. In the recycledplastic material according to the seventh or eighth mode of the presentinvention, ink and its components can be an ink used in an inkjetapparatus.

[0071] In the recycled plastic material according to the eighth mode ofthe present invention, a cleaning solution can be water, and this waterused in cleaning can be reused after being filtered. If this is thecase, a filter for filtering the water preferably has a mesh within therange of 25 to 200 μm.

[0072] Since the cleaning solution is water, the economical efficiencyand the safety of work improve compared to a case in which an aqueouscleaning containing an organic solvent, a surfactant, a builder, and thelike is used. In addition, the load on the environment can be minimizedby repetitively reusing the cleaning solution.

[0073] In the recycled plastic material according to the sixth or eighthmode of the present invention, the step of removing solid matter otherthan thermoplastic can include at least one of gravity separation usingthe true density difference between the thermoplastic and the solidmatter, air classification using the bulk density difference between thethermoplastic and the solid matter, magnetic separation using magneticforce, and metal separation using an eddy current. In the airclassification, the bulk density difference between the thermoplasticand the solid matter to be separated is preferably 0.5 or more.

[0074] The bulk density is the density of pores communicating with theoutside air and internally confined pores in a polycrystallinesubstance, powdery layer, or molded product. The true density is thedensity of a solid itself, which does not include pores.

[0075] The air classification cannot achieve its effect before thecleaning step because a bulk density difference is not easily producedowing to the influence of residual ink, or before the drying stepbecause a bulk density difference is similarly not easily produced. Toreadily produce a bulk density difference, the air classification stepis performed after pulverization, cleaning, or drying. If the bulkdensity difference is less than 0.5, not only the accuracy of precisionseparation decreases, but also the yield of the recycling step lowers.Paper dust not completely removed in the cleaning step can be separatedand removed by this air classification.

[0076] Furthermore, a cleaning solution used in cleaning can be reusedby using a distillation apparatus.

[0077] To reuse a cleaning solution used in cleaning, not only removalof foreign matter by a filter but also adjustment of the pHconcentration described above are combined into one system. Thisimproves the cleanness of the cleaning solution when it is reused andreduce the environmental load.

[0078] The weight ratio of the cleaning solution to the pulverizedthermoplastic can be 10 times or more.

[0079] If the supply ratio of the cleaning solution to the thermoplasticis less than the above value, the probability of the thermoplastic partsto be cleaned overlapping each other increases. This may lower thecleaning effect or make it impossible to reliably remove the cleaningsolution in the subsequent step.

[0080] Inks for printing image information on printing media such aspaper sheets have various compositions for, e.g., writing tools, stamps,recorders, and inkjet printing. Of these inks, inkjet printing ink willbe explained as an example.

[0081] As representative ink, ink containing a plurality of dyes,glycerin, urea, IPA (isopropylalcohol), and pure water will be taken asan example.

[0082] All the dyes are water-soluble, and their balance is designed bytaking account of the clearness upon printing, the concentration, andthe water resistance.

[0083] Glycerin is a high-boiling solvent and has high surface tension.Hence, glycerin is used to prevent clogging of ink channels in an inkjethead, particularly clogging at discharge orifices. Urea is used tofurther enhance this clogging preventing effect and further increase thedye concentration of the ink. Clogging readily occurs especially whenthe amount of dyes in the ink increases, and urea has a function ofpreventing this clogging. IPA has a function of promoting inkpenetration into a printing medium and moisture evaporation duringfixing. This accomplishes both prevention of deterioration of a recordedimage and promotion of fixation. These components are dissolved in purewater to prepare inkjet printing ink.

[0084] When ink having the above composition adheres to a plastic part,moisture evaporates with time, and some of the ink components such asdyes keep sticking to this plastic part. When the sticking amount ofthese ink components is limited to less than 300 ppm, no visualdifference is found between the color of the recycled plastic materialand that of the virgin material.

[0085] If the sticking amount of the ink or the ink components is large,the hue of the final form is influenced.

[0086] In the recycled plastic material according to the fourth oreighth mode of the present invention, gravity separation is preferablyperformed underwater, and the true density difference betweenthermoplastic to be separated and solid matter other than thethermoplastic is preferably 0.5 or more. Ceramics and metal oxideshaving larger true densities than that of thermoplastic are separated bysettling in a cleaning solution such as water. If the true densitydifference is less than 0.5, the efficiency of separation of thesesubstances lowers, and this degrades the yield of the recycling process.

[0087] Magnetic separation preferably uses a magnet having a residualmagnetic flux density of 1 tesla or more. Thermoplastic and solid matterother than the thermoplastic are preferably brought into contact withthe magnetic pole of this magnet.

[0088] Magnetic separation is suitable for ferromagnetic metals. Thecapture ratio of such ferromagnetic substances lowers if a magnet havinga residual magnetic flux density of less than 1 tesla is used.

[0089] In the recycled plastic material according to the first to eighthmode of the present invention, letting I_(R) and M_(R) be the Izodimpact value and the melt flow rate, respectively, of the recycledplastic material, and I_(V) and M_(V) be the Izod impact value and themelt flow rate, respectively, of the virgin material of thermoplasticbefore molding, (I_(R)/I_(V))>0.8 and (M_(R)/M_(V))<1.2 are preferablymet.

[0090] Of the physical property values of thermoplastic, the Izod impactvalue indicates the impact strength of the material and is used toevaluate characteristics such as impact resistance, fragility, andtoughness. When the material deteriorates and embrittles, the Izodimpact value decreases. The melt flow rate (to be abbreviated as MFRhereinafter) is a measure indicating the flowability of thermoplastic ina molten state. The larger the value, the higher the flowability, andthe smaller the molecular weight of the thermoplastic. When the materialdeteriorates, its molecular weight tends to decrease, so the MFRincreases.

[0091] The individual physical property values have variations in virginmaterials. Variations of the Izod impact value and the MFR are said tobe about ±30%. This is a value at one grade of a certain material, andfor the color of the material a plurality of colors are taken intoconsideration. A coloring agent used for coloration contains pigments,dyes, dispersants, and stabilizers. The grade and blending ratio ofthese components change from one color to another. Therefore, for acolor of a certain specific hue, variations of the Izod impact value andthe MFR are small; they can be thought of as about ±25%.

[0092] Also, the physical property values of a recycled plastic materialare highly likely to vary from one lot to another, depending on thestates of collected products as a raw material. Variations in one lotare expected to be slightly larger than those of a virgin material.

[0093] Accordingly, in order for a recycled plastic material to haveperformance equivalent to that of a virgin material, the physicalproperty values must be more severely controlled; variations of the Izodimpact value and the MFR are preferably decreased to ±20% orless.Asdescribedabove, when a material deteriorates the Izod impact valuedecreases and the MFR increases. That is, the Izod impact value and theMFR of a recycled plastic material must be decreased to −20% or less and+20% or less, respectively.

[0094] When the Izod impact value and the MFR which significantly lowerduring the recycling process fall within the above ranges, the qualityof the recycled plastic material is held substantially equal to that ofthe virgin material.

[0095] In addition to the recycled plastic material according to one ofthe first to eighth modes of the present invention, the virgin materialof the thermoplastic before molding can also be used as a raw material.

[0096] Since the basic physical property values are kept in the range ofvariations of a virgin material, even when the amount of a recycledplastic material or the recovery amount of thermoplastic as a rawmaterial varies, the recycled plastic material can be stably supplied bychanging the mixing ratio.

[0097] In the recycled plastic material according to one of the first toeighth modes of the present invention, a thermoplastic material can bean ABS resin (Acrylonitrile Butadiene Styrene RESIN), a PS resin, or aPS-modified PPE resin (Polyphenylene ether RESIN modified byPolystyrene).

[0098] ABS and PS resins are so-called styrene-based polymers. An ABSresin is a copolymer of styrene (CH₂═CHC₆H₅), acrylonitrile (CH₂═CHCN),and butadiene (CH₂═CHCH═CH₂). A PS resin is a homopolymer of styrene(CH₂═CHC₆H₅). An AS resin as a copolymer of styrene and acrylonitrile isalso a styrene-based resin.

[0099] A PS resin has relatively low mechanical strength and isparticularly inferior in impact resistance. High-impact polystyrene(HIPS) is formed by blending an elastic substance such as butadienerubber in order to improve this impact resistance. On the other hand, aPS resin has very high electrical insulating quality and also has goodmolding characteristics since it is superior in thermal stability andflowability in a molten state.

[0100] Acrylonitrile is added to an ABS resin to improve the chemicalresistance and the heat resistance without losing the characteristics ofa PS resin. Butadiene is added to an ABS resin to improve the impactresistance.

[0101] Since both PS and ABS resins are styrene-based polymers and theyhave similar polymer configurations, they are recycled by the sameprocessing.

[0102] When the present invention is applied to a copolymer of adifferent material such as an alloy resin, the recycling conditions whena virgin alloy resin and a single recycled plastic material are mixedmust be different from the recycling conditions when a virgin materialof single plastic and a single recycled plastic material arecopolymerized. Especially when a virgin alloy resin and a singlerecycled plastic material are mixed, a material far from the physicalproperty values of the virgin alloy resin is sometimes formed. As anexample, when a recycled plastic material of an ABS resin is mixed invirgin alloy resins of a PC and ABS, the physical property values dependupon the mixing ratio of this recycled plastic material of the ABSresin. More particularly, in mixing an ABS resin in the PC and ABS alloyresin in a stable polymer alloy state, an excessive amount of the ABSresin to be mixed indicates that incompatible matter with the PC and ABSalloy resin is mixed to influence the physical properties. When arecycled plastic material is used as a raw material for an alloy resin,an alloy resin must be prepared using a control value different fromthat for the virgin material.

[0103] An ABS virgin resin is used for the same ABS material. In thismanner, the use of the same recycled plastic material obviates the needto control fine variations of the physical property values duringpolymerization and thereby simplifies the control of the physicalproperty values of the recycled plastic material.

[0104] A cleaning solution is preferably removed from cleanedthermoplastic by the centrifugal removing method, and the moisturecontent of the final recycled plastic is preferably 0.30 wt % or less.If the moisture content is 0.30 wt % or more, the possibility of theflaky thermoplastic parts sticking to each other increases, and thisproduces adverse effect on thermoplastic which readily hydrolyzes. Also,the cleaning solution removal time is shortened compared to a filteringmethod using a filter, and this prevents deterioration of the color ofthe final recycled plastic material.

[0105] In the electronic apparatus according to the ninth mode of thepresent invention, a recycled plastic material can also include externalparts of the electronic apparatus.

[0106] Since the present invention is applicable to external parts whoseworkmanship is severely evaluated, the physical property values of thematerials can be maintained. In addition, the product value of theexternal appearance does not degrade even when the recycled plasticmaterial is used. This greatly widens the range of applications of therecycled material. Also, the basis of material recycling is ideallyrecycling to a product or a part as a raw material. Therefore, recyclingto an inkjet apparatus (including its parts) is desirable in thisrespect.

[0107] In the method of manufacturing a plastic part according to the10th mode of the present invention, an electronic apparatus can be aninkjet apparatus, and thermoplastic parts can be external members ofthis inkjet apparatus.

[0108] In the method of manufacturing a plastic part according to the11th mode of the present invention, a molded thermoplastic part can be acover plate of an ink container.

[0109] [Embodiments]

[0110] Embodiments in which a recycled plastic material and anelectronic apparatus according to the present invention are applied toan inkjet printer will be described in detail below with reference toFIGS. 1 to 17. However, the present invention is not limited to theseembodiments and is similarly applicable to other techniques to beincluded in the concept of the present invention described in the scopeof claims of this specification.

[0111] An inkjet printer as an object of the present invention prints bydischarging ink from a printing head onto a printing medium. This inkjetprinter has the advantages that the printing means can be made compact,high-definition images can be printed at high speed, images can beprinted on plain paper sheets without any specific processing, therunning cost is low, noise is little because the printer is ofnon-impact type, and color images can be readily printed by using inksof multiple colors.

[0112] The external appearance of this inkjet printer is shown inFIG. 1. That is, an inkjet printer 11 of this embodiment includes anopenable operation cover 14 between an upper case 12 and a lower case13. As shown in FIG. 2, the operation cover 14 can be held open. On theinner surface of this operation cover 14, as shown in FIG. 3 which is anenlarged view of this portion, an illustration 15 depicting operationinstructions of this inkjet printer 11 is laser-engraved. The operationcover 14 including this laser-engraved portion is used as the rawmaterial of a recycled plastic material of this embodiment.

[0113]FIG. 4 shows an outline of the configuration of a recycling systemof this embodiment. That is, a pulverizer 101 pulverizes the rawmaterial of a recycled plastic material into a predetermined size. Aconvey or apparatus 102 conveys the pulverized raw material in units ofpredetermined amounts to a shaking screen 103. Fine particles whichcause clogging or the like in the later work are discharged to a wastetank 104. The raw material which is not sufficiently pulverized iscollected in a collecting tank 105 and returned to the pulverizer 101.The raw material which is pulverized into the predetermined size ispassed through a magnetic separator 106 to capture ferromagnetic metalscontained in the raw material. The resultant raw material is supplied toa hopper 108 of a screw feeder 107. This screw feeder 107 is driven by amotor 109 to supply the raw material in units of predetermined amountsinto a cleaning solution tank 110.

[0114]FIG. 5 shows an outline of the structure of the cleaning solutiontank 110 of this embodiment. That is, the cleaning solution tank 110 ofthis embodiment is partitioned into a plurality of baths to separateplastic as a recycling raw material by using the specific gravitydifference between this plastic and foreign matter such as metals. Theraw material flowing into the final bath is dehydrated by acleaning/dehydrating apparatus 113, which is driven by a motor 112, andsupplied to a cyclone 115 by an air blower 114.

[0115] A cleaning solution W overflowing from an overflow weir 116 ofthe cleaning solution tank 110 is supplied from a buffer tank 117 to adistillation concentrator 118. This distillation concentrator 118supplies a purified cleaning solution to a condensate tank 119, and thecleaning solution is returned to the cleaning solution tank 110. Thedistillation concentrator 118 also discharges the residual solutioncolored by concentrated ink or the like to a concentrated solution tank120.

[0116] A portion of the cleaning solution W overflowing from theoverflow weir 116 is supplied little by little into the screw feeder 107through a filter 121. The supplied cleaning solution is used as alubricating agent to move the raw material in this screw feeder 107.

[0117] The raw material supplied to the cyclone 115 described above isair-classified in this cyclone 115 and dropped in units of predeterminedamounts into an aspirator 123 by a rotary valve 122. A foamedpolyurethane resin (which is contained in a cartridge to be describedlater and functions as an ink holding member) having a smaller bulkspecific gravity than that of the raw material of a recycled plasticmaterial is discharged to a collecting tank 125 by a blower 124.

[0118] The raw material flowing down from the aspirator 123 with metalparticles and the like sticking to it is again passed through a magneticseparator 126 to capture and separate ferromagnetic metal particlessticking to its surface. The resultant raw material is supplied to astock tank 129 of a screw feeder 128 by an air blower 127. The screwfeeder 128 supplies this raw material in units of predetermined amountsto a metal separator 131 for separating metals from the raw material byusing an eddy current or the like. This metal separator 131 separatesmetal particles contained in the raw material and discharges the metalparticles to a collecting tank 132.

[0119] The raw material separated by the metal separator 131 is suppliedinto a hopper 134 by a blower 133 and collected as a final recycledplastic material by a collecting vessel 135.

EXAMPLE 1

[0120] About 40 kg of a raw material were manufactured bylaser-engraving an illustration 20 of operation instructions as shown inFIG. 7 on an operation cover 19 (material: ABS resin, average thickness2.5 mm, true density 1.05) of an inkjet printer (BJC-430J: manufacturedby CANNON INC.) as shown in FIG. 6. This ABS resin does not contain anyfiller or reinforcer for imparting characteristics such as strength,slidability, and flame retardency. A different material such as a nameplate is not adhered to the ABS resin, either.

[0121] A laser engraving machine used in this embodiment is SMU65DT10DK(manufactured by BAASEL LASERTECH, Germany). It has a Nd:YAG laser as alaser source, a wavelength of 1.064 μm, an output of 65 W, a turntablediameter of 1,000 mm, and a lens focal length of 254 mm. This laserengraving machine also includes two engraving heads whose maximumengraving region diameter is 230 mm. It also includes an exhaust pumpwith filter in order to remove fume generated during laser engraving.

[0122] The nozzle of this exhaust pump is set as close as possible tothe laser irradiation position so that the generated fume does not againadhere to the engraved surface of the operation cover 19 to degrade thequality of the engraved portion.

[0123] The line width of one scanning of a laser is an elementdetermined from visibility. For example, the line width need only be 0.3mm when characters laser-engraved on a white plastic material are to beviewed from a position 30 cm away. However, when the engraving contentssuch as operation instructions of particularly an electronic apparatuscontain the illustration 20 as shown in FIG. 7, if an image portion inwhich repetitive scanning lines are densely formed and a characterportion are engraved under the same conditions, the image portion isdeeply engraved. Additionally, the protuberance of the resin around theengraved portion increases in size to break the contour. Thisconsequently lowers the visibility. Accordingly, it is necessary to keepthe balance of molten portions by engraving a plurality of times at thesame depth while gradually shifting the position.

[0124] If the line width is large, the energy of laser increases theamount of discolored matter or carbide which can be foreign matter withrespect to a recycled plastic material. Therefore, a system based on thebalance between the amount of discolored matter or carbide and thevisibility must be considered.

[0125] On the other hand, the deeper the engraved portion, the higherthe contrast between this engraved portion and the surface, so thevisibility improves. However, during recycling a deeper engraved portionis more difficult to clean. This increases the possibility of foreignmatter remaining. To sufficiently supply a cleaning solution to anengraved portion, the section of a scanning line is preferably set to besemicircular. That is, the ratio of the engraving depth to the linewidth is preferably held ½ or less.

[0126] In many laser engraving machines, the scanning rate of anengraving head is variable. The line width and depth of engraving can beadjusted to optimum values by the energy amount of laser and thescanning rate of the engraving head. Consequently, the visibility ofengraving of an image portion and that of a character portion can beheld equivalent to each other.

[0127] The scanning rate depends upon the energy amount of a laserengraving machine used. However, the present inventors examined bytaking the above elements into consideration and have found that toensure visibility and prevent the production of discolored matter orcarbide, it is preferable to set the line width and depth of onescanning of laser to 0.2 mm or less and 0.1 mm or less, respectively.

[0128] Compatibility with a different material is evaluated as follows.For example, a certain substance B is mixed at a weight ratio of C % ina substance A as a reference to measure physical property values. If thephysical property values are equivalent to those of the substance A, thesubstance B is evaluated to have compatibility with the substance A. Inthe evaluation of compatibility label placed on the market, C=1% isgenerally used.

[0129] Since engraving by a laser is superficial, the weight ratiodescribed above must be replaced with the surface area ratio by takingaccount of the thickness of a material to be engraved.

[0130] Of thermoplastics, those said to be suited to recycling do notcontain any reinforcers or fillers. In the case of an ABS resin, PSresin, and PS-modified PPE resin, the thickness of a product ispreferably 3.0 mm or less, except for special molding such asgas-assisted molding, when the transfer properties from a metal moldduring injection molding are taken into consideration. Also, when theload resistance (strength) as a product of an electric/electronicapparatus is taken into account, the thickness must be approximately 2.0mm or more if there is no reinforcement by other members.

[0131] Accordingly, the area of laser engraving is preferably t % orless of the surface area in accordance with a thickness t mm of aplastic part to be engraved, and is preferably 3.0% or less inelectric/electronic apparatuses.

[0132] Alternatively, the line width of one scanning of laser engravingis set to 0.2 mm or less, or the depth of laser engraving is set to 0.1mm or less. This is desirable to use this plastic part as a recycledplastic material.

[0133] When the thickness of product, the energy amount of laser, thevisibility including a protuberance around the engraved portion, and theproductivity (the tact time required for laser engraving, i.e., theirradiation time) are taken into consideration, laser engraving isoptimally done if the laser engraving area is 3% or less of the surfacearea, the line width of one scanning is 0.15 mm or less, and theengraving depth is 0.05 mm or less.

[0134] In this embodiment, the thickness on the irradiated surface ofone line engraved by the emitted laser was 0.12 mm, the depth from theirradiated surface was 0.05 mm, and the engraved area was about 920 mm.The surface area of the operation cover 19 described above was 686 cm,and the area ratio occupied by the laser engraved portion was 1.34%. Theprotuberance of a carbide formed by heat of the laser was not includedin the measurements of the thickness and depth of the line.

[0135] To further improve the visibility of the engraved portion,processing data used in the laser engraving of this embodiment isobtained by partially changing a printing plate commonly used for anoperation cover. For example, in a portion where two lines overlap, oneline is cut to keep the balance of a portion melted by a laser uniformas a whole.

[0136] This operation cover was pulverized by attaching a 6-mm meshscreen to the pulverizer 101 (JC-10: manufactured by Morita Seiki K. K.)shown in FIG. 4.

[0137] The pulverized product was cleaned and the cleaning solution wasremoved by using a cleaning·cleaning solution removing apparatus(HIGHCHIP CLEANER CFP-500: manufactured by Toyo Seiki K. K.,corresponding to 110 and 113 in FIG. 4). The plastic charge rate was 2.5kg/min., and the flow rate of the cleaning solution W (tap water) was 80liters/min. This cleaning solution W was received by the cleaningsolution tank 110 having a capacity of 2,000 liters as shown in FIG. 5.To circulate and reuse the cleaning solution W by using a pump (notshown), the cleaning solution W was filtered by a filter housing(EBF112S6M: manufactured by Loffler K. K.) containing a nylonmonofilament (R100NMO12M bug filter: manufactured by Loffler K. K.,filtering accuracy 100 μm)

[0138] The cleaned pulverized product from which the cleaning solutionwas removed was supplied to an air-classification aspirator system(KF-12: manufactured by Horai K. K., corresponding to 123 in FIG. 4) bythe air blower 114 (DF-5: manufactured by Horai K. K.) and classifiedinto low-bulk-density foreign matter and the other pulverized product.

[0139] The pulverized product passed through the air-classificationaspirator system was dropped onto the magnetic separator 126 (MAGICCATCH: manufactured by JMI K. K., residual magnetic flux density 1.3tesla) to separate ferromagnetic components.

[0140] Subsequently, the pulverized product was conveyed to the stocktank 129 by the air blower 127 (DF-1: manufactured by Horai K. K.) Thispulverized product was conveyed at a ratio of about 3 kg/min. from thestock tank 129 to an eddy current type metal detecting/removingapparatus (MDS-30A: manufactured by Sensor Technology K. K.,corresponding to 131 in FIG. 4), thereby removing metal components. Thefinally obtained cleaned pulverized material weighed 38 kg.

[0141] The amount of moisture sticking to the obtained cleanedpulverized material was measured by the gravimetric method and found tobe 0.11 wt %. Also, residual metal components were visually zero.

[0142] This cleaned pulverized material was pelletized. The obtainedpellets were used to form five sample pieces (based on ASTM-D256: with¼-inch notch) for Izod impact testing, and the Izod impact strength wasmeasured.

[0143] The pelletization process was performed by attaching a 60-meshfilter to an extruder (DMG-40: manufactured by Nippon Purakon) andmelting, kneading, and extruding the material at a cylinder temperatureof 210° C. Izod impact testing sample pieces were formed using thepelletized pulverized material described above by setting an ASTMtesting sample piece family mold in an injection molding machine(IS-80G: manufactured by Toshiba Machine Co., Ltd.) andinjection-molding the material at a cylinder temperature of 200° C.

[0144] Color difference measurement (based on JIS-Z8722 condition D) wasperformed using Izod impact testing sample pieces formed from virginpellets as a color difference standard with respect to the above samplepieces. Analogously, the MFR (based on JIS-K7210: 220° C., load 98.07N)was measured five times. The results are indicated by S₁ in FIG. 13.

[0145] A color difference ΔEab* in FIG. 13 is calculated as perJIS-K7105 by:

ΔEab*=[(ΔL*)²+(Δa*)²+(Δb*)²]⁻²

[0146] The MFR (Melt Flow Rate) described above was measured inaccordance with JIS-K7210B. This method measures the extrusion rate whenmolten thermoplastic is extruded at a prescribed temperature andpressure through a die (a metal block with a shaping mouthpiece) havinga prescribed length and diameter. The method B is an automatic timemeasurement method applied to a material whose MFR is 0.50 to 300 g per10 min.

[0147] A Techno Seven Full-Automatic Melt Indexer (#270) was used as thetesting apparatus. The die (extruding portion) had a length of8.0173±0.025 mm and an inside diameter of 2.092±0.002 mm.

[0148] This testing apparatus was filled with 7 g of a sample (resin)dried at 80° C. for 2 hr at a time. After being preheated at 220° C. for6 min., the sample was extruded at the same testing temperature of 220°C. and a testing load of 98.07N (10 kgf). A time t (sec.) during whichthe piston moved 25.0 mm (L) was measured, and the MFR was calculatedby: MFR  (220, 98.07, B) = 42.6 × L × ρ/t = 42.6 × 25.0 × 0.953/t

[0149] Note that a melt density p of the resin at the testingtemperature was 0.953 g/cm³.

[0150] Before the above recycling process was carried out, the physicalproperty values in virgin pellet state of the material used weremeasured. The results are indicated by R₂ in FIG. 13. Also, to confirmchanges in the physical property values due to injection molding, theabove recycling process was performed using a comparative sample formedwithout laser-engraving the operation cover 19. The results areindicated by R₁ in FIG. 13.

[0151] As shown in FIG. 13, the Izod impact value and the MFR reduced6.3% and 2.9%, respectively, from R_(V) to R₁. From R_(V) to S₁, theIzod impact value reduced 12.5% (6.7% with respect to R₁), whereas theMFR increased 0.6% (3.6% with respect to R₁). To give a recycled plasticmaterial a performance equivalent to that of a virgin material, the Izodimpact strength R_(V) must be 0.8 times or less, and the MFR must beless than 1.2 times. From this viewpoint, the change rates of thephysical property values described above well satisfy thecharacteristics of a recycled plastic material.

[0152] The color difference was evaluated by taking account of colordifference variations in the virgin pellet state. In the case of an ABSresin, variations of color having influence on particularly Δb arelarge, so complement is possible in the same process as a virginmaterial if Δb*≦1.0. Therefore, since ΔEab*=0.88 is mostly composed ofΔb*=0.79, the recycled plastic material can be used in the same manneras the virgin material.

[0153] The residual moisture was also 0.11 wt %, indicating that adverseeffect on plastic caused by hydrolytic properties could be prevented.

[0154] The inkjet printer 11 (BJF-600: available from CANNON INC.) shownin FIGS. 1 to 3 is currently produced and sold by forming all of itsplastic parts by using virgin materials. This inkjet printer 11 wasmanufactured using the cleaned pulverized material obtained through theabove recycling process. More specifically, the cleaned pulverizedmaterial was applied to an upper case 12 (average thickness 2 mm, weight389 g), a lower case 13 (average thickness 2 mm, weight 545 g), and anoperation cover 14 (average thickness 2.3 mm, weight 159 g). FIG. 3shows the state in which the illustration 15 for explaining operationwas laser-engraved on the operation cover 14.

[0155] No difference was visually found between the external appearanceand color (hue, saturation, and lightness) of each of these three partsand a corresponding part manufactured using the virgin material.

[0156] The external surface area of BJF-600 including this operationcover 14 is 4,920 cm², and the surface area of the laser-engravedportion is 920 mm². The ratio of the area of the laser-engraved portionto the external surface area is 0.187%. Compared to the aforementionedexperiment, the area ratio of the laser-engraved portion reduces from1.34% to 0.187%. In addition, a tray 21 for holding printed sheets isalso formed using the same plastic material. Also, the operation cover14 alone need not be recycled in a separate step in the recyclingprocess. It is unlikely to recycle only the operation cover 14 inconsideration of the number of steps.

[0157] Accordingly, the physical property values of the recycled plasticmaterial manufactured using the external parts 12 to 14 of this inkjetprinter 11 are expected to be closer to those of the virgin materialthan the physical property values obtained in the recycling processdescribed above.

Comparative Example of Example 1

[0158] Thermoplastic was recycled following the same procedures as inthe Example 1 except that the contents of laser engraving were printedon a PS resin label (thickness 150 μm) and this label was pasted on theoperation cover 19. The area of the pasted label was 186.2 cm, and itsweight ratio to the operation cover 19 was about 3%.

[0159] The physical property values of this cleaned pulverized material,measured under the same conditions as virgin pellets, were that the Izodimpact value was 97.1 J/m, the MFR was 53.7 g/10 min., and the colordifference ΔE was 1.03. The measured physical property values areindicated by C in FIG. 13.

[0160] As shown in FIG. 13, from R to C, the Izod impact value decreased38.1%, and the MFR increased 10.0%. As described above, to obtain theperformance equivalent to the virgin material, it is necessary to makethe Izod impact strength 0.8 times or less and the MFR less than 1.2times. Therefore, the recycled plastic material obtained from theoperation cover 19 on which the PS resin label having the illustrationformed by printing, instead of laser engraving, was pasted did notsatisfy the required characteristics. Also, the color difference waslarger than 1.0, indicating inferior quality to that of the virginmaterial.

[0161] In the above Example, external members of an inkjet printer areused to form a recycled plastic material. A modification in which thepresent invention is applied to a cartridge of the aforementioned inkjetprinter will be described below.

[0162]FIG. 8 shows the external appearance of the cartridge as an objectof this modification. FIG. 9 shows the exploded state of the cartridge.That is, a cartridge 31 of this modification is formed by integrating aninkjet printing head 32 for discharging ink by using thermal energy andan ink tank 33. This cartridge 31 is mounted to be replaceable in aninkjet printer of the above type.

[0163] The printing head 32 of this cartridge 31 has electro thermaltransducers, formed on a substrate through the semiconductor fabricationprocesses such as etching, vapor deposition, and sputtering, electrodes,liquid channel walls, and a top plate.

[0164] A heater board 34 has a structure in which electro thermaltransducer elements and aluminum lines for supplying power to theseelectro thermal transducer elements are formed by the film formationtechnology. Reference numeral 35 denotes a printed circuit boardcorresponding to the heater board 34, and corresponding lines areconnected by, e.g., wire bonding. A top plate 36 has partitions forlimiting ink flow channels and a common ink compartment. In thismodification, this top plate 36 is formed using thermoplastic having anintegrated discharge port plate.

[0165] Reference numeral 37 denotes a metal base plate; and 38, an SUSpress spring. The base plate 37 and the press spring 38 are combinedwith the heater board 34 and the top plate 36 sandwiched between them.Consequently, the heater board 34 and the top plate 36 are fixed bypressure. The printed circuit board 35 is fixed by adhesion or the liketo the base plate 37. This printed circuit board 35 also functions as amember for radiating heat, generated when ink is discharged, from theheater board 34.

[0166] A sub-tank 39 receives ink supplied from the ink tank 33 as anink supply source and guides the ink to a common liquid compartment,formed by junction of the heater board 34 and the top plate 36, via asupply pipe 40 molded from plastic. An SUS filter 41 is placed in aportion of the sub-tank 39 close to a port for supplying ink to thecommon liquid compartment. This SUS filter 41 is attached by a filterfixing member 42 which is a plastic molded product. Reference numeral 43denotes a cover plate whose pawl 43 a is welded to a boss 39 a formed onthe sub-tank 39. This cover plate 43 is a plastic molded product. An inkholding member 44 to be impregnated with ink is made of a foamedpolyurethane resin and placed in the ink tank 33. A supply port 45supplies ink to a discharge unit including the components 34 to 43described above. In the step before this discharge unit is placed in theink tank 33, the ink holding member 44 can be impregnated with ink byinjecting it from the supply port 45. Reference numeral 46 denotes acover member of the ink tank 33; and 47, an air communicating port whichallows the interior of the cartridge 35 to communicate with the air.

[0167] Ink as disclosed in Japanese Patent Publication No. 7-119378 isknown as ink contained in the ink tank 33 of this cartridge 31. Inkcontaining pigments is also well known as well as ink containing dyes ascoloring agents.

EXAMPLE 2

[0168] 2,000 used cartridges 31 (BC-02: available from CANNON INC.)shown in FIGS. 8 and 9 were collected. As shown in FIG. 10, a coverplate 43, a printing head 32, a printed circuit board, and a base plate37 were removed from an ink tank 33, and the ink tank 33 was cut from acut line L indicated by the alternate long and two short dashed line. Asshown in FIG. 11, an ink holding member 44 accommodated in the ink tank33 was extracted. Consequently, about 30 kg of external members(material: PS-modified PPE, true density 1.08) of the ink tanks 33 wereobtained as a recycling raw material. All of these plastic parts weremanufactured by the same lot. The physical property values in the virginpellet state before use were an Izod impact test value (based onASTM-D256: sample size 2.5×0.5×0.25 (inch), with mold notch) of 90.2J/m, and an MFR (based on ASTM-D1238: 250° C., load 98.07N) of 44 g/10min. The measured physical property values are indicated by R₂ in FIG.14.

[0169] Note that the color difference was calculated by a colordifference expression based on JIS-K7105 from tristimulus valuesobtained in accordance with JIS-Z8722 condition D.

[0170] Of the materials constructing this cartridge 31, materials otherthan the external members are stainless steel for a filter 41 forpreventing clogging of ink discharge ports, PP, PTFE, and glass; andvarious rubber materials and metals as sealing materials, a foamedurethane resin and a porous molded product as the ink holding member 44,and ink. Furthermore, materials constructing the printing head 32 are aglass epoxy substrate, an aluminum substrate, gold and copper as wiringmaterials, and super engineering plastic as a discharge port plate (notshown).

[0171] These used external members were pulverized by attaching an 8-mmmesh screen to the pulverizer 101 (VC-210: manufactured by Horai K. K.)shown in FIG. 4. Ink and its components adhered in an amount of 1,200ppm on the average to this plastic pulverized product. Also, about 200ppm of metals such as the SUS filters 41 and steel spheres (true density7.9) constructing the cartridges 31, which were not completely separatedout, and about 400 ppm of the ink holding members 44 (bulk density0.041) as cut scraps were mixed (both were visually separated out andmeasured by the gravimetric method).

[0172] This pulverized product was cleaned and the cleaning solution wasremoved by using a cleaning·cleaning solution removing apparatus(HIGHCHIP CLEANER CFP-500: manufactured by Toyo Seiki K. K.) The plasticsupply rate was 2.5 kg/min., and the flow rate of the cleaning solutionW (in this embodiment, tap water) was 80 liters/min. The weight ratio ofthe supply amount of the cleaning solution to the supply amount of theraw material per unit time was 32/1. The cleaning solution was receivedby the cleaning solution tank 110 having a capacity of 2,000 liters asshown in FIG. 5. Before being pumped up and reused, the cleaningsolution was filtered by a filter housing (EBF112S6M: manufactured byLoffler K. K.) containing a nylon monofilament (R100NMO12M: manufacturedby Loffler K. K.)

[0173] The cleaned pulverized product from which the cleaning solutionwas removed was supplied to an air-classification aspirator system(KF-12: manufactured by Horai K. K.) by the air blower 114 (DF-5:manufactured by Horai K. K.) and classified into the low-bulk-densityink holding members 44 and the other pulverized product.

[0174] The pulverized product passed through the air-classificationaspirator system was dropped onto the magnetic separator 126 (MAGICCATCH: manufactured by JMI K. K., residual magnetic flux density 1.3tesla) to separate ferromagnetic components.

[0175] Subsequently, the pulverized product was conveyed to the stocktank 129 by the air blower 127 (DF-1: manufactured by Horai K. K.). Thispulverized product was conveyed at a ratio of about 3 kg/min. from thestock tank 129 to an eddy current type metal detecting/removingapparatus (MDS-30A: manufactured by Sensor Technology K. K.), therebyremoving metal components. The finally obtained cleaned pulverizedmaterial weighed 28 kg.

[0176] The amounts of moisture and ink sticking to the obtained cleanedpulverized material were measured by the gravimetric method and thecalorimetric spectroscopy and found to be 0.1 wt % and 90 ppm,respectively. Also, residual metal components and foamed urethane resinwere visually zero. This cleaned pulverized material alone was used toform five Izod impact testing samples (based on ASTM-D256: sample size2.5×0.5×0.25 (inch), with mold notch). The average value of the Izodimpact strengths measured was 89.2 J/m.

[0177] Color difference measurement was performed using Izod impacttesting sample pieces molded from virgin pellets as a color differencestandard with respect to the above sample pieces. The AE was found to be0.43. Analogously, the MFR (based on ASTM-D1238: 250° C., load 98.07N)was measured three times, and the average value was 42 g/10 min. Themeasured physical property values are indicated by S₂ in FIG. 14.

[0178] As shown in FIG. 14, the Izod impact value and the MFR reduced1.1% and 4.5%, respectively, from R₂ to S₂. To give a recycled plasticmaterial a performance equivalent to that of a virgin material, it isnecessary to make the Izod impact strength 0.8 times or less and the MFRless than 1.2 times. The change rates of the above physical propertyvalues well satisfy the characteristics of a recycled plastic material.

[0179] The color difference was evaluated by taking account of colordifference variations in the virgin pellet state. In the case of aPS-modified PPE resin, ΔE≦1.0 was a target. Since ΔE was 0.43, thismaterial can be used in the same manner as the virgin material.

[0180] The residual moisture was also 0.10 wt %, indicating that adverseeffect on plastic caused by hydrolytic properties could be prevented.The residual ink amount was 90 ppm. From these results, the recycledplastic material manufactured by this embodiment is considered to beusable in the same manner as the virgin material.

[0181] To further confirm the characteristics, this cleaned pulverizedmaterial alone was used to mold 100 cover plates 43 of the cartridge 31.Separately, 100 identical comparative samples were molded from virginpellets. 10 plates selected at random from each group were attached to adedicated jig 201 shown in FIG. 12, and the breaking strength of a pawl43 a of the cover plate 43 was measured using a push-pull gauge 202. Theresults are indicated by S₂ in FIG. 15.

[0182] The breaking strength of the pawl 43 a indicated by S₂ in FIG. 15increased 3.1%. This demonstrates that both the bending strength and thetoughness were equivalent to those of the virgin material.

Comparative Example of Example 2

[0183] To confirm the effect of separation of solid matter (to be alsoreferred to as foreign matter hereinafter) such as metals other thanthermoplastic performed after cleaning, a raw material was recycled bythe same recycling process as in the Example 2 except that neither airclassification using the bulk density difference nor metal separationusing eddy current were performed by turning off the air-classificationaspirator system (KF-12: manufactured by Horai K. K.) and the eddycurrent type metal detecting/removing apparatus (MDS-30A: manufacturedby Sensor Technology K. K.)

[0184] The weight of external members of the ink tanks 33 of thecartridges 31 supplied was about 30 kg, and the weight of a cleanedpulverized material obtained was 28 kg. The amount of metal componentscontained was 100 ppm (measured by the gravimetric method). The physicalproperty values of this cleaned pulverized material were an Izod impacttest value of 66.6 J/m, an MFR of 56 g/10 min., and a color differenceΔE of 0.60. The measured physical property values are indicated by C₂ inFIG. 14.

[0185] As shown in FIG. 14, from R₂ to C₂, the Izod impact valuedecreased 26.2%, and the MFR increased 27.3%; the Izod impact valueexceeded 0.8 times, and the MFR was 1.2 times or more. The residualmoisture was 0.25 wt %. Although this value is less than 0.30 wt %, theresidual metal amount was as large as 100 ppm. Consequently, it waspossible to confirm the effects of air classification and metalseparation for a recycled plastic material having a performanceequivalent to that of a virgin material.

EXAMPLE 3

[0186] Cleaning, cleaning solution removal, drying, and precisionseparation were performed following the same procedures as in theExample 2 except that a 6-mm mesh screen was used in pulverization andthe plastic supply rate and the cleaning solution flow rate were set to8 kg/min. and 80 liters/min., respectively, during cleaning. As aconsequence, the cleaned pulverized material obtained weighed 27 kg.

[0187] The physical property values of this cleaned pulverized materialwere an Izod impact test value of 87.2 J/m, an MFR of 43 g/10 min., anda color difference ΔE of0.49. These measured physical property valuesplus the residual moisture and the like are indicated by S₃ in FIG. 14.

[0188] As shown in FIG. 14, from R₂ to S₃, the Izod impact valuedecreased 3.3%, and the MFR increased 2.2%. As described previously, togive a recycled plastic material a performance equivalent to that of avirgin material, it is necessary to make the Izod impact strength 0.8times or less and the MFR less than 1.2 times. The change rates of theabove physical property values well satisfy the characteristics of arecycled plastic material.

[0189] The color difference ΔE was 0.49, and the residual moisture was0.15 wt %; both values were satisfactory to obtain the performanceequivalent to the virgin material. The residual ink amount was 150 ppm.However, when the other physical property values and color differencemeasured are taken into consideration, the quality of this material isconsidered to be equivalent to the virgin material.

[0190] To further confirm the characteristics, this cleaned pulverizedmaterial alone was used to mold 100 cover plates 43 of the cartridge 31.10 plates selected at random from these 100 plates were attached to thededicated jig 201, and the breaking strength of the pawl 43 a of thecover plate 43 was measured using the push-pull gauge 202. The resultsare indicated by S₃ in FIG. 15.

[0191] The breaking strength of the pawl indicated in FIG. 15 increased1.2%. This demonstrates that both the bending strength and the toughnesswere equivalent to those of the virgin material.

EXAMPLE 4

[0192] 40 used inkjet printers (BJC-430: manufactured by CANNON INC.)shown in FIG. 6 were collected to obtain about 40 kg of external members(all made from an ABS resin: true density 1.05) including front covers17, rear covers 18, and operation covers 19. A name plate adhered to thefront surface of each operation cover 19 and rubber legs projecting fromthe bottom surface of each rear cover 18 were removed in advance.

[0193] The physical property values in the virgin pellet state of theABS resin used were an Izod impact test value (based on ASTM-D256: with⅛-inch notch) of 157.8 J/m, and an MFR (based on JIS-K7210: 220° C.,load 98.07N) of 40.7 g/10 min. A maximum of about 700 ppm of ink and itscomponents adhered to this plastic pulverized product (the amount of theadhered ink and its components was measured by the calorimetricspectroscopy). Also, metals or ink holding members not completelyseparated were not found by visual checking. The measured physicalproperty values are indicated by R₂ in FIG. 16.

[0194] Note that the color difference was calculated by a colordifference expression based on JIS-K7105 from tristimulus valuesobtained in accordance with JIS-Z8722 condition D.

[0195] These used external members were pulverized by attaching a 6-mmmesh screen to the pulverizer 101 (JC-10: manufactured by Morita SeikiK. K.) shown in FIG. 4.

[0196] This pulverized product was cleaned and the cleaning solution wasremoved by using a cleaning·cleaning solution removing apparatus(HIGHCHIP CLEANER CFP-500: manufactured by Toyo Seiki K. K.) The plasticsupply rate was 2.5 kg/min., and the flow rate of the cleaning solutionW (in this embodiment, tap water) was 80 liters/min. The cleaningsolution was received by the cleaning solution tank 110 having acapacity of 2,000 liters as shown in FIG. 5. Before being pumped up andreused, the cleaning solution was filtered by a filter housing(EBF112S6M: manufactured by Loffler K. K.) containing a nylonmonofilament (R100NMO12M bug filter: manufactured by Loffler K. K.,filtering accuracy 100 μm)

[0197] The cleaned pulverized product from which the cleaning solutionwas removed was supplied to an air-classification aspirator system(KF-12: manufactured by Horai K. K.) by the air blower 114 (DF-5:manufactured by Horai K. K.) and classified into low-bulk-densityforeign matter such as foamed urethane resin and the other pulverizedproduct.

[0198] The pulverized product passed through the air-classificationaspirator system was dropped onto the magnetic separator 126 (MAGICCATCH: manufactured by JMI K. K., residual magnetic flux density 1.3tesla) to separate ferromagnetic metals.

[0199] Subsequently, the pulverized product was conveyed to the stocktank 129 by the air blower 127 (DF-1: manufactured by Horai K. K.). Thispulverized product was conveyed at a ratio of about 3 kg/min. from thestock tank 129 to an eddy current type metal detecting/removingapparatus (MDS-30A: manufactured by Sensor Technology K. K.), therebyremoving metal components. The finally obtained cleaned pulverizedmaterial weighed 38 kg.

[0200] The amounts of moisture and ink sticking to the obtained cleanedpulverized material were measured by the gravimetric method and thecalorimetric spectroscopy and found to be 0.11 wt % and 10 ppm,respectively. Also, residual metal components were visually zero.

[0201] The physical property values of this cleaned pulverized materialmeasured under the same conditions as virgin pellets were an Izodimpact-value of 145.0 J/m, an MFR of 42.0 g/10 min., and a colordifference ΔE of 0.35. These physical property values measured areindicated by S₄ in FIG. 16.

[0202] As shown in FIG. 16, from R₄ to S₂, the Izod impact valuedecreased 8.1%, and the MFR increased 3.2%. To give a recycled plasticmaterial a performance equivalent to that of a virgin material, it isnecessary to make the Izod impact strength 0.8 times or less and the MFRless than 1.2 times. From this viewpoint, the change rates of the abovephysical property values well satisfy the characteristics of a recycledplastic material.

[0203] The color difference was evaluated by taking account of colordifference variations in the virgin pellet state. In the case of an ABSresin, ΔE≦1.0 was a target. Since the color difference ΔE obtained was0.35, this material was found to be usable in the same manner as thevirgin material.

[0204] The residual moisture was also 0.11 wt %, indicating that adverseeffect on plastic caused by hydrolytic properties could be prevented.The residual ink amount was 10 ppm. From these results, the recycledplastic material manufactured by this embodiment was found to havequality equivalent to that of the virgin material.

[0205] An inkjet printer 11 (BJF-600: available from CANNON INC.) shownin FIGS. 1 and 2 is currently produced and sold by forming all of itsplastic parts by using virgin materials. This inkjet printer 11 wasmanufactured using the cleaned pulverized material obtained through theabove recycling process. More specifically, the cleaned pulverizedmaterial was applied to an upper case 12 (average thickness 2 mm, weight389 g), a lower case 13 (average thickness 2 mm, weight 545 g), and anoperation cover 14 (average thickness 2.3 mm, weight 159 g).Consequently, no visual difference was found between the externalappearance and color (hue, saturation, and lightness) of each of thesethree parts 12 to 14 and a corresponding part manufactured using thevirgin material.

Comparative Example of Example 4

[0206] A material was recycled following the same procedures as in theExample 4 except that the plastic supply rate and the cleaning solutionflow rate of the cleaning-cleaning solution removing apparatus(corresponding to 110 and 113 in FIG. 4) were changed to 2 kg and 10liters/min., respectively. The obtained cleaned pulverized materialweighed 27 kg.

[0207] The physical property values of this cleaned pulverized materialmeasured under the same conditions as virgin pellets were an Izod impactvalue of 121.5 J/m, an MFR of 45 g/10 min., and a color difference ΔE of1.03. These measured physical property values plus the residual moisturecontent and the like are indicated by C₄₁ in FIG. 16.

[0208] As shown in FIG. 16, from R₄ to C₄₁, the Izod impact valuedecreased 23.0%, and the MFR increased 10.6%. As described previously,to give a recycled plastic material a performance equivalent to that ofa virgin material, it is necessary to make the Izod impact strength 0.8times or less and the MFR less than 1.2 times. The recycled plasticmaterial obtained by changing the weight ratio of the cleaning solutionto the pulverized material did not satisfy the necessarycharacteristics.

[0209] Also, the color difference ΔE was 1.03, larger than the criticalvalue of 1.0, the residual moisture content was 0.55 wt %, and theresidual ink amount was 340 ppm. These values and the othercharacteristic values measured indicate that the quality degradedcompared to the virgin material.

Comparative Example 2 of Example 4

[0210] A material was recycled following the same procedures as in theExample 4 except that the filtration accuracy of a filter for a cleaningsolution was changed to 250 μm.

[0211] The physical property values of this cleaned pulverized materialmeasured under the same conditions as virgin pellets were an Izod impactvalue of 117.7 J/m, an MFR of 52 g/10 min., and a color difference ΔE of1.16. These measured physical property values are indicated by C₄₂ inFIG. 16.

[0212] As shown in FIG. 16, from R₂ to C₄₂, the Izod impact valuedecreased 25.4%, and the MFR increased 27.7%. As described previously,to give a recycled plastic material a performance equivalent to that ofa virgin material, it is necessary to make the Izod impact strength 0.8times or less and the MFR less than 1.2 times. The recycled plasticmaterial obtained by changing the filtration accuracy of the filter to250 μm did not satisfy the necessary characteristics.

[0213] Also, the color difference ΔE was 1.16, larger than the criticalvalue of 1.0. This indicates that the quality degraded compared to thevirgin material.

EXAMPLE 5

[0214] In each of the above embodiments, the recycled plastic materialobtained by performing the recycling process of a plastic materialaccording to the embodiment once had physical property values equivalentto those of the virgin material. In this Example 5, physical propertieswhen the recycling process was performed a plurality of times will beexplained.

[0215] Thermoplastic (ABS resin, true density: 1.05) was recycled by thesame process as in the Example 4. The physical property values of virginpellets are indicated by R₅ in FIG. 17. Also, the physical propertyvalues of a recycled plastic material (to be referred to as a “one-timerecycled material” hereinafter) formed by repelletizing the cleanedpulverized material obtained by performing the same recycling process asin the Example 4 one time are indicated by S₅ in FIG. 17.

[0216] The physical property values of a recycled plastic material (tobe referred to as a “two-time recycled material” hereinafter) obtainedby repelletizing the one-time recycled material thus obtained areindicated by S₅₂ in FIG. 17. Also, the physical property values of athree-time recycled material and a five-time recycled material obtainedby similarly repeating the recycling process are indicated by S₅₃ andS₅₅, respectively, in FIG. 17.

[0217] As shown in FIG. 17, both the Izod impact value and the MFR ofthe one-time recycled material obtained by performing the recyclingprocess according to the present invention decreased 2.3% compared tothe virgin material (R₅) Also, the color difference was 0.22. Thesevalues can be regarded as equivalent to those in the Example 4. That is,the one-time recycled material was found to be usable in the same manneras the virgin material.

[0218] Likewise, lowering (deterioration) of the physical propertyvalues of the two-, three-, and five-time recycled materials withrespect to the virgin material (R₅) was most significant in S₅₅; theIzod impact value decreased 7.2%, the MFR increased 2.3%, and thelowering of the color difference was 0.51.

[0219] In the present invention, the definition of a recycled plasticmaterial having a performance equivalent to a virgin material is thatthe Izod impact strength is 0.8 times or less, the MFR value is lessthan 1.2 times, and the color difference is 1.0 or less. When thisdefinition is taken into consideration, each physical property valueshows that this recycled plastic material can be used in the same manneras the virgin material.

[0220] The Rockwell hardness of each recycled material was substantiallythe same value as the virgin material. This physical property value alsoindicates that the physical property values of these recycled plasticmaterials fell in the ranges of prescribed values.

[0221] That is, the present invention is effective even when therecycling process is performed a plurality of times.

[0222] In the present invention, laser-engraved thermoplastic is used asthe raw material of a recycled plastic material. Therefore, therecycling process of this recycled plastic material does not require anylabel peeling step. Also, since no paint such as used in silk screenprinting sticks to the material, the recycling process can besimplified, and deterioration of the hue of the obtained recycledplastic material can be prevented.

[0223] Furthermore, an electronic apparatus having laser-engravedthermoplastic parts is disassembled, and thermoplastic parts of anidentical electronic apparatus are molded using thermoplastic obtainedfrom the thermoplastic parts of the disassembled electronic apparatus asa raw material. This allows ideal recycling to be performed.

[0224] Since thermoplastic containing metals is used as the raw materialof a recycled plastic material, not only the metals contained in thethermoplastic as the raw material but also most metal pieces which canbe mixed when the raw material is pulverized during the recyclingprocess can be easily removed. Therefore, contamination is very little,so recycled plastic having high external appearance quality can beobtained.

[0225] When thermoplastic used in an inkjet apparatus or thermoplasticto which an ink or its composition adheres is used as the raw materialof a recycled plastic material, this thermoplastic can be directlyreused as thermoplastic parts of the original inkjet apparatus.

[0226] Since an electronic apparatus is constituted by using therecycled plastic material described above, the use and spread of thisrecycled plastic material can be further promoted.

[0227] When a cleaning solution after thermoplastic is cleaned isfiltered through a filter having a mesh within the range of 25 to 200 μmand the filtered cleaning solution is reused, the problem of thephysical properties of the obtained recycled plastic material and theproblem of clogging of the filter can be solved at the same time.

[0228] When a cleaning solution contains at least one of an additive foradjusting the pH concentration and a surfactant, the cleaning effect canbe obtained within a short time.

[0229] When water is used as a cleaning solution and this water used incleaning is filtered and reused, the economical efficiency and thesafety of work can be increased compared to the case in which an aqueouscleaner containing an organic solvent, surfactant, and builder is used.Additionally, the load on environment can be minimized by repetitivelyreusing the cleaning solution.

[0230] When a cleaning solution after cleaning is to be reused, not onlyforeign matter removal using a filter but also pH concentrationadjustment are combined into one system. This improves the cleanness ofthe cleaning solution when it is reused and reduces the environmentalload.

[0231] By limiting the amount of adhesion of an ink or an ink componentsto a recycled plastic material to less than 300 ppm, the color of therecycled plastic material can be made equal to that when a virginmaterial is used.

[0232] Letting I_(R) and M_(R) be the Izod impact value and the meltflow rate, respectively, of a recycled plastic material and I_(V) andM_(V) be the Izod impact value and the melt flow rate, respectively, ofa thermoplastic virgin material before molding, the quality of thisrecycled plastic material can be kept substantially equal to that of thevirgin material if (I_(R)/I_(V))>0.8 and (M_(R)/M_(V))<1.2.

[0233] When external parts of an electronic apparatus are formed by arecycled plastic material, the product value of the external appearancedoes not degrade even with the use of the recycled plastic material, aswell as the physical property values of the material are maintained.This greatly widens the application of the recycled material unlike inconventional thermal recycle or cascade recycle.

[0234] Furthermore, ideal recycling can be performed becausethermoplastic obtained from thermoplastic parts of an ink container usedin an inkjet apparatus is used as a raw material and thermoplastic partsof an identical inkjet apparatus are molded using this raw material.

[0235] The present invention is not limited to the above embodiments andvarious changes and modifications can be made within the spirit andscope of the present invention. Therefore, to apprise the public of thescope of the present invention the following claims are made.

What is claimed is
 1. A recycled plastic material made from laser-engraved thermoplastic.
 2. A recycled plastic material manufactured by pulverizing laser-engraved thermoplastic, cleaning the pulverized thermoplastic, removing a cleaning solution from the cleaned thermoplastic to dry said thermoplastic, and removing from the dried thermoplastic solid matter other than said thermoplastic.
 3. A recycled plastic material made from thermoplastic containing a metal.
 4. A recycled plastic material manufactured by pulverizing thermoplastic containing a metal, cleaning the pulverized thermoplastic, removing a cleaning solution from the cleaned thermoplastic to dry said thermoplastic, and removing from the dried thermoplastic solid matter other than said thermoplastic.
 5. The material according to claim 4, characterized in that after said thermoplastic is pulverized, said thermoplastic and said metal are classified before said thermoplastic is cleaned.
 6. The material according to claim 4, characterized in that the step of removing said solid matter comprises at least one of gravity separation using a true density difference between said thermoplastic and said solid matter, magnetic separation using a magnetic force, and metal separation using an eddy current.
 7. The material according to claim 4, characterized in that said gravity separation is performed underwater, and a true density difference between said thermoplastic and said solid matter to be separated is not less than 0.5.
 8. The material according to claim 4, characterized in that said magnetic separation uses a magnet having a residual magnetic flux density of not less than 1 tesla, and said thermoplastic and said solid matter are brought into contact with a magnetic pole of said magnet.
 9. A recycled plastic material made from thermoplastic used in an inkjet apparatus.
 10. A recycled plastic material manufactured by pulverizing thermoplastic used in an inkjet apparatus, cleaning the pulverized thermoplastic, removing a cleaning solution from the cleaned thermoplastic to dry said thermoplastic, and removing from the dried thermoplastic solid matter other than said thermoplastic.
 11. The material according to claim 10, characterized in that ink and components thereof, paper dust, and dust sticking to said thermoplastic are removed by cleaning said thermoplastic.
 12. The material according to claim 10, characterized in that after said thermoplastic is pulverized, said thermoplastic and foreign matter are classified before said thermoplastic is cleaned.
 13. The material according to claim 10, characterized in that said cleaning solution used in cleaning is filtered through a filter having a mesh within the range of 25 to 200 μm, and the filtered cleaning solution is reused.
 14. The material according to claim 10, characterized in that said cleaning solution contains an additive for adjusting pH concentration.
 15. The material according to claim 10, characterized in that said cleaning solution contains a surfactant.
 16. The material according to claim 10, characterized in that the step of removing said solid matter comprises at least one of gravity separation using a true density difference between said thermoplastic and said solid matter, air classification using a bulk density difference between said thermoplastic and said solid matter, magnetic separation using a magnetic force, and metal separation using an eddy current.
 17. The material according to claim 10, characterized in that said cleaning solution used in cleaning is reused by a distillation apparatus.
 18. The material according to claim 10, characterized in that a weight ratio of said cleaning solution to said pulverized thermoplastic is not less than 10 times.
 19. The material according to claim 10, characterized in that an amount of ink and components thereof sticking to said thermoplastic after said solid matter is removed is less than 300 ppm.
 20. A recycled plastic material made from thermoplastic to which ink and components thereof have stuck.
 21. A recycled plastic material manufactured by pulverizing thermoplastic to which ink and components thereof have stuck, cleaning the pulverized thermoplastic, removing a cleaning solution from the cleaned thermoplastic to dry said thermoplastic, and removing from the dried thermoplastic solid matter other than said thermoplastic.
 22. The material according to claim 21, characterized in that said cleaning solution is water, and water used in cleaning is filtered and reused.
 23. The material according to claim 21, characterized in that a filter for filtering said water has a mesh within the range of 25 to 200 μm.
 24. The material according to claim 21, characterized in that said ink and composition thereof are ink used in an inkjet apparatus.
 25. The material according to claim 21, characterized in that the step of removing said solid matter comprises at least one of gravity separation using a true density difference between said thermoplastic and said solid matter, air classification using a bulk density difference between said thermoplastic and said solid matter, magnetic separation using a magnetic force, and metal separation using an eddy current.
 26. The material according to claim 21, characterized in that a bulk density difference between said thermoplastic and said solid matter to be separated by said air classification is not less than 0.5.
 27. The material according to claim 21, characterized in that said cleaning solution used in cleaning is reused by a distillation apparatus.
 28. The material according to claim 21, characterized in that a weight ratio of said cleaning solution to said pulverized thermoplastic is not less than 10 times.
 29. The material according to claim 21, characterized in that an amount of ink and components thereof sticking to said thermoplastic after said solid matter is removed is less than 300 ppm.
 30. The material according to claim 21, characterized in that said gravity separation is performed underwater, and a true density difference between said thermoplastic and said solid matter to be separated is not less than 0.5.
 31. The material according to claim 21, characterized in that said magnetic separation uses a magnet having a residual magnetic flux density of not less than 1 tesla, and said thermoplastic and said solid matter are brought into contact with a magnetic pole of said magnet.
 32. The material according to claims 2, 4, 10 and 21, characterized in that letting I_(R) and M_(R) denote an Izod impact value and a melt flow rate, respectively, of said recycled plastic material and I_(V) and M_(V) denote an Izod impact value and a melt flow rate of a virgin material of said thermoplastic before molding, (I_(R)/I_(V))>0.8 and (M_(R)/M_(V))<1.2 are met.
 33. A recycled plastic material made from the material according to claims 2, 4, 10 and 21 and a virgin material of thermoplastic before molding.
 34. The material according to claims 2, 4, 10 and 21, characterized in that said thermoplastic is one of an ABS resin, a PS resin, and a PS-modified PPE resin.
 35. An electronic apparatus comprising the material according to claims 2, 4, 10 and
 21. 36. The apparatus according to claims 2, 4, 10 and 21, characterized in that said recycled plastic material includes an external part of said electronic apparatus.
 37. A method of manufacturing a plastic part, comprising the steps of: disassembling an electronic apparatus having a laser-engraved thermoplastic part; separating said thermoplastic part from the disassembled electronic apparatus and pulverizing said thermoplastic part; cleaning the pulverized thermoplastic; removing a cleaning solution from the cleaned thermoplastic to dry said thermoplastic; removing from the dried thermoplastic solid matter other than said thermoplastic; and molding a thermoplastic part of said electronic apparatus by using said thermoplastic, from which said solid matter is removed, as a raw material.
 38. The method according to claim 37, characterized in that said electronic apparatus is an inkjet apparatus, and said thermoplastic part is an external member of said inkjet apparatus.
 39. A method of manufacturing a plastic part, comprising the steps of: disassembling an ink container used in an inkjet apparatus; separating a thermoplastic part from the disassembled ink container and pulverizing said thermoplastic part; cleaning the pulverized thermoplastic; removing a cleaning solution from the cleaned thermoplastic to dry said thermoplastic; removing from the dried thermoplastic solid matter other than said thermoplastic; and molding a thermoplastic part of said inkjet apparatus by using said thermoplastic, from which said solid matter is removed, as a raw material.
 40. The method according to claim 39, characterized in that said thermoplastic part to be molded is a cover plate of said ink container.
 41. A recycled plastic material manufactured by recycling a part molded from a thermoplastic material, characterized in that an impact strength of said recycled plastic material is not less than 80% of a virgin plastic material, and a melt flow rate (MFR) of said recycled plastic material, which indicates the flowability of a plastic material is 90 to 120% of the virgin plastic material.
 42. The material according to claim 41, characterized in that said molded part is a plastic part having a laser-engraved surface.
 43. The material according to claim 41, characterized in that the surface area of a laser-engraved portion of said molded part for recycling is kept not more than 3.0% of the surface area of said molded part.
 44. The material according to claim 41, characterized in that the line width and the depth of the laser-engraved portion of said molded part for recycling are not more than 0.2 mm and not more than 0.1 mm, respectively.
 45. The material according to claim 41, characterized in that said molded part for recycling is a part of an electric/electronic apparatus, and the laser-engraved portion is a technical information display.
 46. The material according to claim 41, characterized in that the part of said apparatus is a printer part.
 47. A method of manufacturing a recycled plastic material, characterized in that in order to recycle a part molded from a thermoplastic material, plastic is repelletized through steps of pulverization, cleaning, drying, and foreign matter removal of said molded part, and an impact strength and a melt flow rate (MFR) of said plastic pellets are adjusted within the ranges of predetermined values.
 48. A method of reusing a plastic material, characterized in that a part is molded from a plastic material, said molded part is used as a part after a laser engraving display is formed on said molded part, a recycled plastic material is formed through steps of pulverization, cleaning, drying, and foreign matter removal of said part, and an impact strength of said recycled plastic material falls within a predetermined range of an impact strength of a virgin plastic material.
 49. The method according to claim 42, characterized in that the impact strength of said recycled plastic material is not less than 80% of the impact strength of the virgin material.
 50. A method of reusing a plastic material, characterized in that a plastic material is molded into an ink container and used as a part, a recycled plastic material is formed through steps of pulverization, cleaning, drying, and foreign matter removal of said part, and physical property values of said recycled plastic material fall within predetermined ranges of physical property values of a virgin plastic material.
 51. The method according to claim 50, characterized in that an impact strength of said recycled plastic material is not less than 80% of an impact strength of the virgin material.
 52. A method of manufacturing a recycled plastic material, characterized in that a recycling raw material is obtained by successively performing, in the order named: the pulverizing step of pulverizing a part molded from a thermoplastic material by using a mesh screen of 4 to 10 mm; the cleaning step of cleaning a pulverized material obtained in the pulverizing step by using 10 parts by weight of water as a cleaning solution with respect to 1 part by weight of said pulverized material; the dehydrating step of dehydrating said pulverized material cleaned in the cleaning step by centrifugal dehydration to set a moisture content to not more than 0.30 wt %; the foamed body removing step of removing, by air classification, a foamed body having a bulk density difference of not less than 0.5 from said pulverized material dehydrated in the dehydrating step; the first metal removing step of removing a metal from said pulverized material by using a magnet having a residual magnetic flux density of not less than 1 tesla; and the second metal removing step of removing a metal by using a metal detecting/removing device, and recycled plastic pellets are obtained by successively performing, in the order named: the mixing step of sufficiently mixing said recycling raw material; the recycling step of melting, kneading, and recycling said recycling raw material by an extruder; and the pelletizing step of pelletizing the material recycled in the recycling step.
 53. The method according to claim 52, characterized in that said thermoplastic part is a part having a laser-engraved surface.
 54. The method according to claim 52, characterized in that said thermoplastic part is a part of an electric/electronic apparatus.
 55. The method according to claim 52, characterized in that said thermoplastic part is a part to which an ink or a composition thereof have stuck.
 56. A recycled plastic material manufactured by the method according to claim 52, characterized in that an Izod impact strength and a melt flow rate of said recycled plastic material are not less than 80% and 90 to 120%, respectively, of virgin pellets. 